As an example, IFNγ has been implicated in the cognitive deficit of Down syndrome, a neurodevelopmental disorder characterized by an extra copy chromosome 21 (chromosome 16 in mice), which codifies for many IFN-regulated genes and IFN receptors,49, 50 with patients displaying increased levels of this cytokine18 and increased sensibility to IFN action. The gene discussed is IFNG; the disease is Down syndrome.